Blake, 25, was caught on speed cameras twice earlier this year but, when asked if it was him driving the car, he said it was his non-driving grandad Thomas behind the wheel.

The sentence comes just two years after Blake got Mr Clarkson into trouble for using his mobile phone at the wheel on the M40 in Oxfordshire.

He got his friend to take a photo of Mr Clarkson before sending it to national newspapers where it was published along with comments from Blake.

In the one newspaper he was quoted as saying: “Everyone knows you can’t use a phone behind the wheel. Perhaps he thinks he’s above the law.”

But Blake, of Froxfield Down, discovered he wasn’t above the law when he was snapped in Bracknell doing 49mph in a 40mph zone in January.

He already had nine points on his licence and, knowing that the extra three points for the offence would probably mean he would lose his licence, wrote to his grandad to ask him to take the blame.

His grandad agreed and then when Blake was caught doing 71mph in a 50mph zone in Bagshot, Surrey, in March, he repeated the trick.

But police checked the speed camera pictures which clearly show it was Blake, not his grandad, behind the wheel.

Mr Clarkson told The Standard: “Prison for such a trivial offence seems harsh, but somewhere in this muddle justice has been done.”

Blake appeared in Banbury Magistrates’ Court on Thursday, July 29, where he admitted perjury, for which he was jailed, and two counts of speeding, for which he has been banned from driving for six months.

Magistrates told him: “This case is so serious that we feel custody is the only sentence we can impose.

“Your grandfather became a vulnerable victim of your actions to protect you out of family loyalty.”

PC Pat Knight of Thames Valley Police’s fixed penalty support unit said: “Mr Blake had nine penalty points on his licence at the time of the first speeding offence.

“He saw the opportunity to continue habitually speeding by coercing an elderly relative into helping him.”